diff --git a/lib/Minilisp.pm b/lib/Minilisp.pm
index 7eb2269..2d1d303 100644
--- a/lib/Minilisp.pm
+++ b/lib/Minilisp.pm
@@ -202,21 +202,32 @@ sub macro_let {
 
   while ($ts->[0]->{type} != RPAREN)
     {
-      my $ident = shift @$ts;
-      die "Expected identifier in let" unless $ident->{type} == IDENT;
+      $tok = shift @$ts;
+      die "Expected pair in parameter list in let" unless $tok->{type} == LPAREN;
 
-      my $assignment = parser_expr($ts);
+      my $ident = shift @$ts;
+      die "Expected identifier in pair in parameter list in let" unless $ident->{type} == IDENT;
+
+      my $assignment;
+      if ($ts->[0]->{type} == RPAREN)
+        {
+          $assignment = sub { return undef };
+        }
+      else
+        {
+          $assignment = parser_expr($ts)
+        }
+
+      $tok = shift @$ts;
+      die "Expected ) after parameter pair" unless $tok->{type} == RPAREN;
 
       $pctx->{$ident->{value}} = $assignment;
     }
 
   $tok = shift @$ts;
-  die "Expected ) after assignments in let" unless $tok->{type} == RPAREN;
+  die "Expected ) after parameter list in let" unless $tok->{type} == RPAREN;
 
-  my $inner = parser_expr($ts);
-
-  $tok = shift @$ts;
-  die "Expected ) after let" unless $tok->{type} == RPAREN;
+  my $inner = macro_progn($ts);
 
   return sub {
     my $octx = shift;